Re: [net-next 11/13] igb: Make Tx budget for NAPI user adjustable

Ben Hutchings
2011-09-17T17:04:11Z

On Sat, 2011-09-17 at 01:04 -0700, Jeff Kirsher wrote:
> From: Alexander Duyck <alexander.h.duyck@intel.com>
>
> This change is meant to make the NAPI budget limits for transmit
> adjustable. By doing this it is possible to tune the value for optimal
> performance with applications such as routing.
[...]
> --- a/drivers/net/ethernet/intel/igb/igb_ethtool.c
> +++ b/drivers/net/ethernet/intel/igb/igb_ethtool.c
> @@ -1989,6 +1989,9 @@ static int igb_set_coalesce(struct net_device *netdev,
> if ((adapter->flags & IGB_FLAG_QUEUE_PAIRS) && ec->tx_coalesce_usecs)
> return -EINVAL;
>
> + if (ec->tx_max_coalesced_frames_irq)
> + adapter->tx_work_limit = ec->tx_max_coalesced_frames_irq;
> +
[...]

I don't think it really makes sense to conflate NAPI and interrupt
moderation parameters. This really ought to be added to NAPI itself.

(NAPI contexts really ought to be exposed through sysfs somehow. I
think we've discussed this before, and it's tricky due to the lack of a
consistent mapping between those contexts and net devices.)

Ben.

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Ben Hutchings, Staff Engineer, Solarflare
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